P-selectin (CD62, GMP140, PADGEM) is a membrane glycoprotein of .about.140 kDa expressed by activated platelets and vascular endothelial cells. In resting platelets and vascular endothelial cells P-selectin is sequestered in p granules [Hsu-Lin, S., et al., J. Biol. Chem., 259, 9121-9126 (1984); and Stenberg, P. E., J. Cell Biol., 101, 880-886 (1985)] and Weibel-Palade bodies [McEver, R. P., et al., J. Clin. Invest., 84, 92-99 (1989); and Bonfanti, R., et al., Blood, 73, 1109-1112 (1989)], respectively. In response to inflammatory mediators such as thrombin [Hsu-Lin, S., et al., J. Biol. Chem., 259, 9121-9126 (1984); and Stenberg, P. E., J. Cell Biol., 101, 880-886 (1985)], histamine [Hattori, R., et al., J. Biol. Chem., 264, 7768-7771 (1989)], complement components [Hattori, R., et al., J. Biol. Chem., 264, 9053-9060 (1989)], or peroxides [Patel, K. D., et al., J. Cell Biol., 112, 749-759 (1991)] and cytokines such as interleukin-1 and tumor necrosis factor, P-selectin is rapidly mobilized from these intracellular stores to the cell surface where it mediates the initial binding interactions of activated platelets with leukocytes and the vascular wall, and of leukocytes with activated vascular endothelial cells. P-selectin is a member of a family of adhesion molecules which includes E-selectin (ELAM-1), which is expressed by activated vascular endothelial cells, and L-selectin (Leu 8, LAM-1, LECAM), which is expressed by leukocytes. These proteins are type I membrane proteins and are composed of an amino terminal lectin domain followed by an epidermal growth factor (EGF) like domain, a variable number of complement receptor related repeats (CR), a hydrophobic membrane spanning region and a cytoplasmic domain. As indicated by high sequence homology, these proteins are not only structurally but also functionally related, modulating the trafficking of peripheral blood leukocyte by permitting adhesive interactions between leukocytes and endothelial cells. These binding interactions are predominately mediated by contacts between the lectin domain of the selectin and various carbohydrate ligands.
Although it is now widely accepted that a lectin domain/carbohydrate interaction is primarily responsible for mediating P-selectin/myeloid cell binding, the exact molecular nature of the P-selectin ligand is not knowns. Binding of P-selectin to myeloid cells is Ca.sup.2+ dependent as well as neuraminidase and protease sensitive. The binding of P-selectin to myeloid cell lines can be inhibited by growing the cells in the presence of sodium selenate and inhibitor of sulfation. P-selectin has been shown to bind to the carbohydrate Le.sup.x (CD15) [Larsen, E., et al., Cell, 63, 467-474 (1990)] and its sialylated form, sialyl-Le.sup.x (sLe.sup.x) [Erbe, V. E., et al., J. Cell Biol., 119, 215-217 (1992)], and there is evidence that these carbohydrates and/or others like them are presented to P-selectin by a discrete number of cell surface proteins including L-selectin. Various anionic polymers, including heparin, fucoidan, and dextran sulfate have also been shown to inhibit P-selectin mediated adhesion [Skinner, M. P., et al., Biochem. Biophys. Res. Commun., 164, 1373-1379 (1989); and J. Biol. Chem., 266, 5371-5374 (1991)]. In addition, P-selectin has been shown to bind 3-sulfated galactosyl ceramides (sulfatides) [Aruffo, A., et al., Cell, 67, 35-44 (1991)]. Although the physiological relevance of this interaction remains to be elucidated, it is known that myeloid cells can excrete large quantities of sulfatides on activation. This suggests that sulfatides might participate in leukocyte extravasation at sites of inflammation by displacing the adhesion-mediating leukocyte surface ligand(s), thereby permitting the efficient exit of leukocytes from the blood stream at sites of inflammation.
A number of publications have appeared which describe new agents as inhibitors of cellular adhesion. Some of these publications, but not limited to, include the use of peptides and carbohydrate structures in International patent application WO 92/01718 published Feb. 6, 1992; the use of substituted lactose and lactosamine derivatives in International patent application WO 93/10796 published Jun. 10, 1993; the use of glycoconjugates in International patent application WO 93/05803 published April 1, 1993; the use of sulfated glycolipid derivatives by Y. Suzuki, et al., Biochem. Biophys. Res. Commun., 190, 426-434 (1993) and the use of oligosaccharides by M. S. Mulligan, et al., Nature, 364, 149-151 (1993).
However, there are many situations in which the recruitment of leukocytes by adhesion to the endothelial cells is abnormal or in excess, and the end result is tissue damage instead of repair. Thus, there is a need to develop specific and potent compounds which can inhibit the initial cellular adhesion process. It is the object of the present invention to provide new sulfated glycolipids which are inhibitors of cell adhesion and, therefore, useful in man for the treatment and/or prevention of acute or chronic inflammatory diseases such as rheumatoid arthritis, asthma, allergy conditions, psoriasis, septic shock and other indications such as reperfusion injury, adult respiratory distress syndrome, ischemia, ulcerative colitis, vasculitides, atherosclerosis and inflammatory bowel disease, multiple sclerosis and tumor metastases.